The present invention relates to signal detection apparatus for use in a satellite communication system, for example. The invention, more particularly, relates to a burst signal detecting apparatus in which the probability of reception of erroneous data can be controlled to an extremely small value.
The present invention is applicable to made up of a unique word followed by data that is CRC (Cyclic Redundancy Check) coded and error-correcting coded. A prior art signal detection apparatus for detecting this type of burst signal basically comprises an error-correcting decoder, a CRC error detector, a UW detector, and an output circuit for providing a signal indicating the presence or absence of error in the burst signal.
In the foregoing, prior art signal detection apparatus, the UW detector detects a unique word from the burst signal and delivers to the output circuit an arrival signal, which is representative of the arrival of the data. The error-correcting decoder decodes the error-correcting code used with regard to the data in the burst signal, and feeds the decoded data to the CRC error detector. In response, the CRC error detector performs a cyclic check on the decoded data to see if the received data is free from error, delivers the received data as output data to an external circuit, and provides an output decision signal, indicating presence or absence of error, extends to the output circuit. Upon receiving the arrival signal, if the error signal indicates absence of error, the output circuit sends, the output signal to the external circuit indicating that there are no errors in the output data.
A problem with the prior art signal detection apparatus described above is that the probability of reception of incorrect data cannot be easily reduced. This stifles improvements in the reliability of a communication channel, as discussed in detail below.